Railway signaling



May 18 1926. 1,584,991 F. H. NICHOLSON RAILWAY SIGNALING Original FiledApril 21, 1921 iNVENTOR I H-w. ATTORNEY Patented May 18, 1926.

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FRANK H. NICHOLFSON, 0F PHILADELPHIA, PENNSYLVANIA, ASSIG'NOR TO THEUNION S'WITGH s SIGNAL COMPANY, OF SWIISSVALE, IENESYLVANIA, ACORPORATION OF PENNSYLVANIA.

RAILVIAY SIGNALZNG.

Original application filed April 21, 1921.

Renewed January 22, 1923, Serial No. 463,234. Divided and thisa-Pplieation filed November 17,1924. Serial No. 750,293.

My invention relates to railway signaling, and particularly to signalingof the type wherein roadside signals are controlled in accordance withthe presence and absence of trains through the medium of track circuits.

I will describe one form of signaling apparatus embodying my invention,and will then point out the novel features thereof in claims. 1

The present case is a division of my copending application, Serial No.463,234, filed Jan. 22, 1923, as a renewal of my original application,filed April 21, 1921, for railway signaling.

The accompanying drawing is a diagrammatic view showing one form ofsignaling apparatus embodying my invention.

Referring to this drawing, the reference characters E and E designatethe track rails of a stretch of railway track over which trafiicnormally moves in the direction indicated by the arrow. These trackrails are divided, by means of insulated joints 2, into a plurality ofsuccessive track sections A B, B-C, etc., and each section is providedwith a roadside signal which is designated by the reference character Swith an exponent corresponding to the location. As shown in the drawing,each of these signals is of the semaphore type, adapted to indicateSt-op, Caution or Proceed according as the semaphore blade is in thehorizontal, inclined or Vertical position.

Each track section provided with a track circuit comprising atransformer designated by the reference character T with an exponentcorresponding to the location, the secondary of which transformer isconnected across the rails adjacent the exit end of the section. Theprimary of each transformer T is supplied with alternating current fromsome suitable source such as an alternator l, overa transmission line Asher .hown the supply of such current toeach transformer is control ed bya pole changer operated by the adjacent signal and designated by thereference character P with a suitable exponent. Each pole changer isoperated during the movement of the signal between stop and cautionpositions, and so the section in the rear of an occupied section issupplied with alternating current of one relative polarity, which I willterm the reverse polarity, whereas all other sections are supplied withcurrent of the opposite relative polarity, which I will term normalpolarity.

Each track circuit also comprises a transformer designated H with asuitable exponent, the primary of which is connected across the trackrails at the entrance end of the section, and the secondary of whichcontrols the corresponding signal S through-the medium of apparatuswhich I will now describe.

Each signal S is controlled directly by a relay designated by thereference character F with a suitable exponent. Each of these relays isof the usual direct currenttype, having a neutral armature responsive tothe presence and absence of current, and a polarised armature responsiveto the direction of flow of current through the relay winding. Thewinding for this relay is in two sections, designated 27 and 27, whichsections are connected at the middle so that the relay is what may betermed a dill'erential polarized relay. That is, if current flows intothe relay through wire 28 and passes through the upper section 27, theneutral aunature will be closed and the polarized armature will be swungto one extreme position. if current enters the relay through wire 28,but flows through the lower section 52?, the neutral armature will stillbe closed but the polarized armature will he swung to its oppositeerztreme position.

The supply of energy to each relay 1 is controlled by two electron tubesD and 1) associated therewith and each comprising, as usual, a filament5, a. grid 6, and a plate Each section is further provided with atransformer designated by the reference character 5 with an appropriateexponent. The primary 15 of each such transformer d is constantlysupplied with alternating cur rentfrom transmission line 3.

Referring particularly to location it, the signal S is provided with acaution indication circuit which passes from a secondary 29 oftransformer J through wire 30, nontral contact 31 of relay F wire 32,operating mechanism ofsignal S, and wire 33 to secondary 29. The signalis also provided with a proceed indication circuit which passes fromsecondary 29, through wire .30,

contact 31 of relay 1*, wire 3i, polarized contact of relay F, wire 36,operating mechanism of signal S, and wire 33 to secondary 29. Thecaution indication circui of course, closed when eith r winding of relayF" energized, but the proceed indication circuit is closed only whencontact 35 is swung to the left, and this occurs only when the upperwinding 27 is energized. The controlling circuits for each of theremaining signals are the same as those for signal S Still referring tothe apparatus associated with signal S, the relay F is supplied withcurrent from a secondary 16 or the transformer J and this supply isgoverned by the two electron tubes'D and D associated therewith, whichin turn are controlled by the transformer H. The electron tube filaments5 are heated by a secondary S on transformer J these filaments as hereshown being connected in series. Tube D is provided with a grid circuitwhich passes from the right hand terminal of secondary 23 of transformerH through wire 25, grid (3 and filament 5 of tube D, and wires 38 and2-1 to the middle point of secondary 23. Similarly, the grid 6 of tube Dis connected with the left hand terminal of secondary 28 through a wire26, while the filament 5 of this same tube is connected with the middlepoint of secondary 23 by wires 41. 2e and 2f. It will be seen from theforegoing. that at any given instant the polarities of the grids 6 ofthe two tubes D and D are opposite; that is, when the grid of tube D ispositive with respect to its associated filament, the grid of tube D 15negative with respect to its associated filament.

The circuit for the secondary 16 of trans former J comprises twobranches, one of which includes section 2? of the winding of relay F andelectron tube D, whereas the other branch includes section 27 of therelay winding and electron tube D First considering tube D, the completeplate circuit for this tube is from the left hand terminal of secondary16, through wire 28, section 27 of the winding of relay F wire 37, tubeD", and wires 38, 9A and 39 to right hand terminal of secondary 16. Asfor tube D the complete plate circuit is from secondary 16, through wire28, section 27 of the winding of relay F wire 40, tube D and wires alland 39 to secondary 16.

The primary 15 of transformer J is connected with the transmission line3, and the parts of the apparatus are so adjusted that the plate circuitvoltages in tubes D and D are either substantially in phase with, ordisplaced substantially 180 from the grid voltages applied to thesetubes by transformer H It follows that when pole changer P is in oneposition, the grid 6 of tube D will be positive with respect to thefilament at the same instant that the plate 7 of this tube is alsopositive with respect to the filament. hen this is the case, currentwill flow freely from seeonary 16 through tube D and winding sec tion 2?of relay F, but substantially no current will flow through tube 1) andsection 27, because the grid of this tube is negative with'respect tothe filament at the instant that the plate 7 is positive with respect tothe filament. The arrangement is such that tube D is thus conductivewhen signal S indicates caution or proceed, that is. when track sectionBC is unoccupied. When pole changer P is reversed, however, it will beobvious that current will flow freely through tube D but thatsubstantially no current will flow through tube D, so that windingsection 2? of relay F will be supplied with current but section 27 willbe tie-energized. It will be seen, therefore, that the relay F isenergized only when track section A.B is unoccupied, and that thepolarized arn'iature of relay F is closer or open according as sectionI"; C is unoccupied or occupied.

As shown in the drawing, tracl: s ction (1-D is occupied by a car ortrain ll", so that the supply of current to transformer H isdiscontinued. The potential in the electron tube plate circuit-s due totrans former J is relatively low, so that the currents flowing throughthe windings of relay F are small when the grid circuits of tubes D andD are (lo-energized. Furthermore, the currents that flow through winding27 and 27 of relay F neutralize each other in their etl'cct upon neutralarmature 31, because these currents are substantially equal, and theyflow in opposite directions through the relay winding. It should also benoted that when transformer H is (lo-energized, that is, when the grids(i are de-encrgized, tlu s rall currents in the plate circuits due tosecondary 16 will flow on the positive half wave only, there being noflow in the opposite direction on the consecutive hall" waves. Relay Fis, therefore, open so that signal indicates stop. Pole changer 1",which is operated by signal S", is in such position as to supply currentof reverse rclative polarity to the rails of section B C. The result ofthis is that tube D at signal S is rendered conductive, so that"winilingsection 27 of relay F is supplied with current. This causes energizationof relay F in such direction that its polarized contact is open, withthe result that signal S indicates caution. The pole changer P istherefore in such position that current of normal relative polarity issupplied to the rails of section i l-13, so that tube D for this sectionis rendered conductive. This causes winding section 27 of relay F to beenergized, so that polarized contact 35 of this relay is closed, withthe result that signal 8* is in the proceed posltion.

Although I have herein shown and described only one form of signalingapparatus embodying my invention, it is understood that various changesand modifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim-is:

1. In combination, a section of railway track, a track circuit for saidsection including a source of current reversibly connected with therails; two electron tubes each having a heated filament, a grid and aplate; a grid circuit for each tube energized from said track circuit insuch manner that when the grid of either tube positive with respect toits filament the grid of the other tube is negative with respect to itsfilament; a plate circuit connected with a source of alternating currentand provided with two branches including said two tubes respectively; apolarized relay having two difii'erential windings included in the twobranches of said late circuit and si naling 7 Z: Q

means controlled by said relay.

In combination, a section of railway track, a track circuit for saidsection in cluding a source cl current reversiblyconnected with therails; two electron tubes each having a heated filament, a grid and aplate; a grid circuit for each tube energized from said track circuit insuch manner that when the grid of either tube is positive with respectto its filament the grid of the other tube is negative with respect. toits filament; a plate circuit connected with a source of alternatingcurrent and provided with two branches including said two tubes,respectively; and signaling means for giving one indication or anotheraccording as a substantial current flows in one branch or the other ofsaid plate circuit.

3. In combination, a section 0'? railway track, a track circuit for saidsection including'a source of current reversibly connected with therails; two electron tubes each having a heated filament, a grid and aplate; a grid circuit for each tube energized from said track circuit insuch manner that when the grid of either tube is positive with respectto its filament the grid of the other tube is negative with re spect toits filament; a plate circuit con nected with a source of alternatingcurrent and provided with two branches including said two tubes,respectively; a plate circuit for each tube including a source ofalternating current substantially in phase with,

or displaced 180 from the track circuit current; and signaling means forgiving one indication or another according as a substantial currentflows in oneroi' said plate circuits or the other.

4:. In combination, a section of railwayv track, a track circuitfor saidsection ineluding a source of alternating current reversibly connectedwith the rails, two electron tubes, a grid circuit for each tubeenergized from said traclr circuit, a plate circuit for each tube, saidplate circuits being so connected that one plate circuit or the other isconductive according to the relative polarity of the track circuitcurrent, a polarized relay having two differential windings included insaid two plate circuits respectively, and signaling means con trolled bysaid relay.

5. In combination, a section of railway track, a track circuit for saidsection including a source of alternating current reversibly connectedwith the rails, two electron tubes, 9. grid circuit for each tubeenergized from said track circuit, a plate circuit for each tube, saidplate circuits being so connected that one plate circuit or the other isconductive according to the relative polarity of the track circuitcurrent, and signaling means controlled by said plate circuits.

6. In combination, a section of railway track, a. track circuit for saidsection including a source of alternating current reversibly connectedwith the rails, two electron tubes each having a grid circuit ar rangedto receive energy from the track circuit, two plate circuits one foreach said tube, a polarized relay controlled by said plate circuits inaccordance with the relative polarity of the track circuit current, andsignaling means controlled by said polarized relay.

7. In combination, a section of railway t ack, a track circuit for saidsection in cluding a source of energy revesibly connccted with therails, two other circuits for said section, means controlled by therelative polarity of the track circuit current in said track circuit forvarying the resistances of said other circuits, a polarized relaycontrolled in accordance with the resistances of said two othercircuits, and signaling means controlled by said relay.

8. In combination, a section of railway traclt, a track circuit for saidsection in- ClUCllllg a source of energy reversibly connected with therails, two other circuits for said section, means controlled by therelative polarity of the track circuit current in saidcircuit forvarying the resistances o'l said other circuits, a polarized relaycomprising two differential winding sections included in said two othercircuits respectively, and signaling means controlled by said rela I 9.In combination, a section of railway track, a track circuit for saidsection in-- eluding a source of ei'ierg'y reversibly con-- neeted vviththe rails, a polarized relay having two (lill'erentizil \vin'tlings afirst electron tulle having a grid circuit receivingenergv from saidtrack circuit and adapted to supply current to one said Winding when thetrack circuit current is of one relative p0" luritvr 11 second electrontlllK! having a grid circuit receiving energy from the track cir 1U cuitand adapted to supply current to the remaining relay winding when thetruck circuit current is ol the other relative polarity. and signalingmeans controlled by said relay.

In testimony whereof I :ll'lllx' in sig'uu- 15 ture.

FRANK H. liltlllOlJSOIQ.

